Perhaps the ultimate example is the encyclopedia article on Uqbar in the Anglo-American Cyclopedia, described as "a literal if inadequate reprint of the Encyclopædia Britannica of 1902," which declares that "mirrors and copulation are abominable, since they both multiply the numbers of men." Uqbar exists only in the mind of JL Borges, or course.

I think my favorite book within a book is the unnamed work by Robert Cohn, of which Jake Barnes said, "He wrote a novel, and it was not really such a bad novel as the critics later called it, although it was a very poor novel.”

As one of the proprietors of the Invisible Library, I'm here to say thanks for the suggestions, several of which we wouldn't have thought of.

We're just getting started, so the collection's a bit hit-or-miss--our Fellowes Kraft entry, for example, includes just what I came across on a quick flip through The Solitudes; a more systematic search awaits. And a friend reminded me about the Douglas Adams titles last night, so they're there now.

More to come, and suggestions are welcome, either in comments at the blog itself on each letter or e-mailed to thedizzies_at_gmail.com

(All these are merely titles: maybe you're only including books from which passages are available.)

Dictionary of the Devils, Deities and Daemons of Mankind by Alexis Payne de St.-Phalle

Some others: There's the book in "Books Do Furnish a ROom" that Jenkins complains "came in 25000 words too short and titled 'Than Whom What Other'," but I don;t remember if it had an author. And there are the books by the avant-garde postwar novelist X. Trapnel: "Portraits in String" and "Camel Ride to the Tomb".